Create, remove and update tenants to accept both single items and lists

[sebawita]

Currently, the create, update, and remove tenant functions require us to provide a list of Tenant objects, even if we are dealing with one tenant object.

It would be nice, to have an option to either provide a single tenant object (without wrapping it in a list) or a list (the current behaviour).

papers.tenants.create(
    Tenant(name="ten-name")
)

papers.tenants.update(
    Tenant(name="ten-name", activity_status=TenantActivityStatus.HOT)
)

papers.tenants.remove("ten-name")

[tsmith023]

Implemented in #973